Machines for excavating graves and the like have, in general, been largely commercially impractical because of various problems involved in their construction and operation. Grave digging machines typically include a support frame of some type which remains at all times upon the surface of the ground. An excavation assembly that is supported by the frame, usually loosens the earth to be excavated and transports the earth out of the gravesite.
Grave digging machines may typically be classified into one of two categories. The first category includes grave diggers which excavate the grave by both a horizontal and a vertical movement of an excavation assembly such as is illustrated in U.S. Pat. No. 3,577,664 issued to T. J. Sing. Typically, an endless conveyor which is elongated in a vertical direction is initially moved vertically into the ground until a portion of the vertical conveyor is below the surface of the ground. Then the excavation assembly, including the vertical conveyor, is moved horizontally so as to excavate the grave along its length.
Typically grave diggers which operate in this manner require a number of horizontal passes in order to excavate a grave of desired dimensions. Since these grave diggers excavate the grave by the movement of an excavation assembly in a horizontal direction, the excavation assembly usually exerts a considerable horizontal force on the support frame. Consequently, the support frame of the grave digger must include means so as to remain stationary with respect to the surface of the ground. In loosely packed soil, the ground engaging means of the support frame of the grave digger may slide horizontally and thereby destroy grass and other vegetation surrounding the gravesite.
Grave diggers of the second category excavate the grave by a single vertical movement of an excavation assembly. Like the other grave diggers, these excavators generally include a support frame which remains at the surface of the ground. An exacavation assembly is usually supported by the frame, but is restricted to movement with respect to the frame in a vertical direction only. Consequently, these grave diggers are typically not subjected to the considerable horizontal forces of the first category of grave diggers.
The excavation assembly generally includes an endless conveyor which is of the same general horizontal dimensions as a grave, when the conveyor is viewed from below. A grave is excavated by lowering the excavation assembly vertically downward until the grave has been excavated to a desired depth. Grave diggers of this category may operate more quickly and more efficiently than other grave diggers because the excavation requires a single pass of the excavation assembly. Grave diggers which operate in a generally vertical direction also may utilize the weight of the grave digger to urge the excavation assembly into vertical engagement with the earth.
However, grave diggers which excavate the earth by a vertical movement of an excavation assembly have been costly and expensive to operate because of the enormous size of the endless conveyor used in their construction. One type of grave digger, such as is illustrated in U.S. Pat. No. 2,501,083 issued to W. A. Owen, uses the same endless conveyor which loosens the earth from beneath the excavation assembly to transport the earth out of the grave. If the length of the conveyor which carries the digging implements can be minimized, not only can the overall cost of the machine be reduced, but also the expense of operation of the grave digger may be decreased.
Accordingly, it is an object of the present invention to provide a novel grave digger which excavates a grave in a single vertical pass of an excavation assembly that is economical in cost and operation by reason of a shortening of the length of the conveyor which carries the digging implements of the excavation assembly.
It is another object of the present invention to provide a novel grave digger having a plurality of endless conveyors to remove the loosened earth from the excavation thereby permitting a shortening of the length of the endless conveyor that carries the digging implements of the excavation assembly.
Grave diggers which utilize the same endless conveyor to both loosen the earth from below the excavation assembly and to transport the loosened earth out of the grave, typically have a rather high center of gravity. The center of gravity of grave diggers may be significantly lowered if the heavy endless conveyor which carries the digging implements may travel only at the lower end of the excavation assembly. A low center of gravity for the grave digger would result in greatly increased stability during operation of the machine.
Accordingly, it is yet another object of the present invention to provide a novel grave digger having an endless conveyor for carrying digging implements that travels in a path located at the lower portion of an excavation assembly thereby resulting in a grave digger having a low center of gravity and a greatly increased stability during the excavation of a grave.
Very often it is desirable to be able to excavate graves of a cemetery during the day while the cementary may be open to the public. However, the noise that results from the operation of a grave digger tends to disturb the peaceful, quite atmosphere that is characteristic of many cemeteries. Therefore, it is oftentimes necessary to excavate graves only while the cemetery is closed to the public such as during the night.
In spite of the use of mufflers and other noise reducing devices, much of the noise that results from a grave digger which is powered by an internal combustion engine is actually due to the operation of the engine itself. If the noise of the engine could be reduced, the grave digger may be operated while the cemetery is open to the public without causing a disturbance to visitors to the cemetery.
Accordingly, it is still another object of the present invention to provide a novel grave digger which is powered by an internal combustion engine that is relatively quiet in operation as a result of a location of the engine on the grave digger. The engine, located above the excavation assembly travels into the grave as excavation proceeds, so that the grave itself may direct and muffle the sound.
The length of various caskets varies considerably between one another, such as between children's and adult's caskets. Because of the expense involved in the excavation of a grave and because of the close proximity of caskets in some cemeteries, it is oftentimes a requirement that graves of different lengths be excavated. Previous grave diggers which operate in a horizontal movement of an excavation assembly, such as those cited above, are capable of excavating graves of different lengths merely by limiting the horizontal travel of the excavation assembly. Grave diggers which excavate a grave in one vertical movement of an excavation assembly, however, have been unable to be easily adjusted so as to excavate graves of different lengths because of the massive structure necessary to support the chain of the excavation assembly.
Accordingly, a further object of the present invention is to provide a novel grave digger which may easily be adjusted so as to enable graves of different lengths to be excavated in single vertical movements of an excavation assembly.
Yet another object of the present invention is to provide a novel grave digger which may be adjusted by means of a slidably removable axle and rollers so as to enable graves of different lengths to be excavated in single downward movements of an excavation assembly.
These and other objects of the invention will become apparent from the claims and from the following description when read in conjunction with the appended drawings.